1. Technological Field
The invention relates to preventing fraudulent access to a telecommunications system. In particular, the invention relates to identifying fraudulent calls originating at a particular telephone number (an “originating automatic number indicator” or “originating ANI”).
2. Description Of The Related Art
Fraud costs the telecommunications industry billions of dollars per year. There are many techniques used to perpetrate fraud. The fraud can be as simple as using a stolen credit card to charge a long distance call, or it can involve sophisticated looping techniques, such as repeatedly calling a private PBX system, finding the correct sequence to access an outside line (by trial and error or other hacking techniques) and then placing a costly long distance call through the PBX system. The telecommunications industry is involved in an intensive and ongoing effort to identify different types of fraud and then to develop and implement ways of preventing such fraud.
Fraud is more costly to certain telecommunications companies than others. For example, where a fraudulent call is directed at a company that owns the underlying telecommunications infrastructure, the cost of the call is less than the cost to an independent company that incurs access charges to the owner(s) of the infrastructure supporting the call, even if the call is fraudulent. In either case, however, the cost to the industry is significant.
Particular methods of fraud control and systems for implementing them are known in the industry. Fraud control may be divided conceptually into identifying a call that is likely to be fraudulent and responding after a call is identified as likely to be fraudulent. Methods of identifying calls that are likely to be fraudulent vary from the simple to the sophisticated and are generally directed at a particular type of fraudulent activity. For example, a call is likely to be fraudulent if it is made using a calling card that has been reported stolen by the owner.
A more sophisticated method and system of identifying fraudulent calls is described in U.S. Pat. No. 5,768,354, entitled “Fraud Evaluation And Reporting System and Method Thereof”, which is owned by the assignee of the present invention. Fraudulent activity is identified in the '354 patent by monitoring a billing detail record created for each call. In the simple case, where the company's database shows that the billing number being used for a call has been reported lost, stolen, etc., the billing detail record includes a header designating it is a “bad billing number”, the call is immediately identified fraudulent and an alert is generated in the system.
The '354 patent is directed at calls that require “special service”, that is, which are placed through an operator or an automatic operation support system. Such calls generally require the caller to manually supply the billing number, such as by pressing numbers on a payphone, swiping the magnetic strip on a card or speaking with an operator. It may also require the caller to identify the category of billing product (such as credit card, calling card, or pre-paid phone card) for the billing number. The category of the billing product may alternatively be identified by the system by matching all or part of the billing number with billing numbers (or ranges of billing numbers) stored in an identification database, where the stored billing numbers are correlated with the category of billing product. The identification database may also correlate a billing number with the particular type of billing product for the category. For example, where the category of the billing number is identified as a credit card, the identification database may use the billing number to further identify the type of credit card, such as Visa, Master Card, American Express, etc.
The '354 patent also identifies fraudulent activity by monitoring use of a billing number over time. For example, where the number of domestic calls placed within a certain amount of time using the same billing number exceeds a threshold, an alert is generated. International calls are similarly handled, however, the threshold may be adjusted so that fewer calls within the time period generate an alert. In addition, the threshold may be further adjusted for calls to countries where a high percentage of fraudulent calls are directed. The thresholds may also be varied by the billing product. For example, fraudulent activity may be determined to be more likely to occur on a calling card than on a third party call; consequently, the threshold may be set lower for calling card products.
Once a call initiates an alert that the call might be fraudulent, additional activity may be taken to further examine whether the billing number is being used fraudulently, or steps may be taken to prevent further calls using the billing number. In the '354 patent, after an alarm is generated, data for prior calls charged to the billing number are sent to a fraud analyst, who analyzes that data and may determine whether or not to deactivate the card. If the decision is to deactivate the card, the '354 patent describes the analyst as setting a fraud flag.
While monitoring billing numbers and blocking those numbers displaying evidence of fraudulent usage is an important component of fraud prevention, no one technique in itself is sufficient to prevent fraudulent access. Perpetrators of fraud (also referred to herein as “hackers”) are persistent and creative and are constantly developing new ways of evading fraud prevention mechanisms. In addition, there is a ready (and relatively inexpensive) supply of stolen billing numbers available to those who are so disposed to obtain and use them. Thus, the fraud detection and prevention techniques that focus on billing numbers, such as the '354 patent, may not be effective against hackers who have a supply of different billing numbers.
For example, a series of fraudulent calls may be made from a single originating ANI over time. One prominent example of this type of fraudulent activity is when an attempt is made to hack into a private PBX in order to access information or to use the PBX to make a subsequent call. In the latter case, the call to the PBX may be a local or domestic call, which is less likely to attract attention, whereas the subsequent call made from the PBX may be a costly international call. If such calls are made using different billing numbers, then the fraud will not be prevented based on fraud prevention techniques that rely on repeated use of a billing number.
Repeated calls to a PBX (or other terminating ANI) may be identified and blocked using certain methods that create alerts based on fraudulent calling patterns to the terminating ANI and, once identified, block or otherwise intercept subsequent special services calls to the terminating ANI. Such techniques may not be feasible for many terminating ANIs, however. For example, where the terminating ANI is a busy hospital, it may be unacceptable to block incoming calls under any circumstances, even if a fraud alert on the terminating ANI is generated.
Thus, it would be desirable to have a system and technique for identifying and blocking fraudulent calls made from an originating ANI where a number of different billing numbers are used to place the calls. So-called “back end” procedures for identifying fraudulent calling patterns from originating ANIs rely on analysis of calling records in batch and identifying unexpected billing patterns in light of the type of originating ANI. Such batch analysis, however, can be sporadic and typically occurs long after the fraudulent calling starts, for example, days, weeks or even months. This can allow the fraudulent activity to occur for lengthy periods before it is identified and prevented. It would therefore also be desirable to have a system and method for blocking such fraudulent calls that identifies potentially fraudulent calling patterns using up-front processing, i.e., is close in time to the beginning of the fraudulent calling activity.